The present invention relates generally to a method and apparatus for monitoring fuel cell voltages in a fuel cell stack, and more particularly to making connector and component failures in the monitoring circuitry transparent to the user without losing the information that the failed connector or component was designed to provide. Furthermore, the method and apparatus provide for a redundant power supply and ground connection for the monitoring circuitry measurements.
Fuel cells produce energy by the electrochemical processing of reactants and the subsequent generation of electric current. A typical fuel cell configuration includes a polymer membrane (e.g., a proton exchange membrane (PEM)) with catalyst layers on both sides to promote the respective oxidation and reduction of hydrogen and oxygen. Additional components, including a pair of gas diffusion media layers disposed against the respective catalyst layers and cathode and anode bipolar plates placed outside the gas diffusion media layers; these bipolar plates define flow channels therein to facilitate the introduction of the externally-provided reactants to the catalyst-coated PEM. The various components are compressed together to form the fuel cell. To increase the power output, numerous fuel cells are arranged together to form a fuel cell stack.
Fuel cell stacks are monitored for their electrical viability through a set of diagnostic connectors which are attached to the bipolar plates of each fuel cell within the fuel cell stack. An embedded measurement module (EMM), via the diagnostic connectors, monitors the voltage of each fuel cell and reports that health to the vehicle electronic control unit (ECU).
A problem with this approach is that the EMM is unable to address any failure modes that may arise, making the system vulnerable to diagnostic connector and component failures. Furthermore, if the diagnostic connector that powers the EMM fails, the EMM will not provide any information on any of the fuel cells to the vehicle ECU. A way is needed to circumvent those failures to get the needed data to monitor the health of the fuel stack.